7.3 idi none turbo stalling when stoping

Colin Mccormick

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I have a 1993 f350 with a 7.3 idi and it jeeps stalling when im stoping or rpm are high and let of gas and then it stalls. But it will stay running no problem just when i bring up rpm and let of gas fast or drive and try to down shift so when i let of gas and then it stalls any ideas of what it could be thanks for you input
 

Big Bart

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FYI you put this in the power stroke forum, more folks will respond if you put in th 6.9/7.3 idi forum.

Some initial thoughts are -

See if your throttle arm on your IP is jumping off to the side of idle adjust screw on the IP pump if you slam the throttle closed. Since it seems to be only when the throttle slams closed you have an issue.

Does your throttle linkage not return all the way unless it slams closed? Perhaps you need to adjust your idle screw so the pump arm does not go too far back and cause a lack of fuel.

Have you changed your fuel filter in the last 15k miles?

When did you last rebuild your IP pump?
 

gandalf

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You've described the classic symptoms of a stuck metering valve in the IP.

Step one would be to fill the fuel filter with a good cleaner. Start the engine and let it run until you hear a slight change in engine sound, maybe as much as two minutes. Shut the engine off and let it sit overnight. The cleaner will be in the IP doing it's thing. The next day start it up and drive it hard, drive it like you stole it.

Frequently this will free the metering valve and the problem will be over. However, this is often the first sign that the IP is getting old and will need replacement in the not too distant future.

What I've left out is the name of a good cleaner. We used to use ATF, but apparently the detergents have been removed from the current ATF. Some one will come along with the name of a good cleaner.
 

Colin Mccormick

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Thanks so much for help im going to try to do a liqui moly flush and let sit and chang fuel filter i have never rebuild ip pump but something to consider i will update on whether this fixes it or not then mess with idle screw and stuff like that thanks again and i thought i was in the 7.3 idi forums still new to this page
 

IDIBRONCO

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If that doesn't work, I'd look at your mechanical lift pump next. Your issues also sound like what happens when the lift pump gets weak. A test is to let the engine wind down as you come up to a stop keep down shifting and letting out on the clutch pedal until you're almost stopped. If you can do that and it keeps running, that points toward the lift pump.
 

riotwarrior

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I think Gandalf might be onto something.

Colin is my son and I am far away and cannot assist easily thus I send him here.

I shared my tech 101 liqua-moly diesel purge w him so he will try that Gandalf.
 
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